Improvement in parallel rulers



.TAYLOR vParallel Ruler,

A PatentedvAug.3l,1875.

N. PETERS, PHOTo-'urnoemtmm WASHINGTON. D fz4 'UNITED STATES PATENT OFFICE.

` JOHN M. TAYLOR, OE BOSTON, MASSACHUSETTS.

l IMPROVEMENT IN PARALWLEL RULERS.

Specification forming part of Letters Patent No. [66,320, dated August 3, 1875; application liled Apri114, 1875.

To all whom it may concern:

Be it known that IJOHN M. TAYLOR, of Boston, of the county of Suffolk and State of Massachusetts, have ,made a new and useful.

- ings, is intended for ruling parallel lines, either at equal distances apart or at gradually-increasing distances asunder, to represent the shading of a round or cylindrical surface. For this purpose the ruler, composed oftwo bars or rules, connected by a series of two or more junction-links of equal lengths pivoted to the rules, is furnished with a mechanism to operate in moving one ruler equal distances toward the other, or at unequal or shading distances.

The two rules are shown atA and B as con,- nected by the links C G C as in acommon parallel ruler. To the base ruler B there is applied a ,spiral or volute spring, 5, having its l inner end fixed to a rotary arbor, a, provided with an arm orhandle for revolving it in order to wind up the spring. The outer end of the sprin g is hooked upon a stud, c, projectingfrom the lniddle connection-link C. Furthermore, there is applied to the ruling-rule A either a straight toothed rack, 13, or a curved quadrantal rack, 14, the teeth of each being triangular or like sawteeth. The straight rack is for enabling parallel lines at equal distances apart to be ruled by means of the instrument, the curved rack being to enable parallel lines at variable distances apart to be ruled by means of such instrument, and by a pen or pencil. The curved rack is pivoted at or near .one 'end tothe bar A, the pivot being shown at d. The straight rack, however, arranged at a.

right angle to the rule A, is supported by and so as to be capable of sliding laterally on a rail, 12, iixed on said urule A. In order to facilitate its movement on the rail the rack is connected with the outer link G by a short link, c, pivoted to the rack and to the link C, as shown. The distance between the axes of the pivots of the link-c is half` thatl between those of the pivots by which the bar C is connected to the tWori1`lesA B. In Fig. l the dotted lines represent the positions ofthe principal parts when the rule Ais at its maximum distance from the base rule B. Either rack is to be operated by an escapement mechanism arranged in a case or box, j'. vIn said box is a lever, 6, which, at its middle, turns freely on a fulcrum. To this lever, at its opposite ends, two pawls, 7 and 8, are `jointed, one of which-viz., that marked S-extends between two guides, g h, and has at one side of it a projection or shoulder, t'. A spring, 1, arranged in the box, is to force the pawl 8 forward. There is also in the box a sp1-ing, 2, arranged, as shown, to press the pawl 7 toward an adjusting-screw, l1, screwed into the side of the box. ,An angular lever, 15,l is pivoted to the boX,and has its lower arm resting against the shoulder i. In order to keep the rack up to a guide or lever abutment, 10, pivoted to the ruler B, and notched, as shown, to receive a latch or catch, 7c, a spring, 3, fastened to the box f, may be used, the spring being caused to bear against the toothed edge of the rack.

By pressing down the upper arm of the lever 15 the pawl 8 will be forced back outot` engagement with the rack, the pawl 7 being at the same time shot forward into engagement with it. The instant the iirst pawl may leave the rack the second pawl will engage with such rack, and asV soon as the pawl 8 leaves the rack such rack, by the contractileforce of the spring 45, will be moved lengthwise, and will continue tomove until the pawl 7 may bring up against the abutment or guide g. Thus the ruler A will be moved toward the ruler B by the spring 5 a short distance, determined by the movement of the pawl 7, up to the guide or stop g. On removing the hand from the lever l5 the spring l will cause the pawl 8 to be shot `forward up to the rack, and the pawl 7 to be moved backward, the spring 2 in the meantime throwingthe pawl 7 back against the adjustingscrew. By means of the said screws the lateral movement of the pawl 7 may be determined, so as to cause it to pass over one or ing-edge of the lirst ruler against the starting line, to Which a series of lines are to be drawn parallel, he should press with his left hand the ruler B down upon the paper, and with one finger thereof suddenly depress the lever 15. O11 this being done, the ruler A Will immediately be moved by the spring 5 the necessary distance toward the ruler B for the ruling of the first line. In like manner he is to press after each line may have been ruled.

What I claim as my invention is as follows: 1. The combination of the spring 5, the

toothed rack 13 or 14 and an escapement, substantially as described, with the two rules A B, connected by links O C, all being to operate essentially as specified.

2. The said escapement, substantially as described, composed of the lever 6, pawls 7 8, lever 15, guides g 71., and springs l and 2, arranged and combined as specified.

3. The adjustable abutment or screw 11, in combination with the escapelnent, and to operate therewith, as and. for the purpose eX- plained.

4. The straight rack 13, applied to the rule A, to slide rectilinearly thereon, and connected to the link C by the shorter link e, all being substantially as described.

JOHN M. TAYLOR. Witnesses:

R. H. EDDY, J. R. SNOW. 

